Indebtedness - Narrative (Details)		1 Months Ended											12 Months Ended
	Dec. 21, 2023 USD ($)	Dec. 31, 2023 USD ($) property	Apr. 30, 2023 USD ($) property	Feb. 28, 2023 USD ($)	Jan. 31, 2023 USD ($)	Oct. 31, 2022 USD ($) property	Jul. 31, 2022 USD ($) property	Jun. 30, 2022	Apr. 30, 2022 USD ($) property	Feb. 28, 2022 USD ($)	Feb. 28, 2021 USD ($)	Feb. 07, 2021	Dec. 31, 2023 USD ($) property	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jun. 30, 2023 USD ($)	Jan. 31, 2022 USD ($)	Jun. 30, 2021 USD ($)
Debt Instrument
Repayments of borrowings on revolving credit facility													$ 700,000,000	$ 100,000,000	$ 0
Loss on modification or early extinguishment of debt													2,468,000	30,043,000	2,410,000
Accrued interest		$ 22,847,000											$ 22,847,000	29,417,000
Number of properties owned (property) | property		371											371
Redemption of senior unsecured notes													$ 250,000,000	500,000,000	$ 300,000,000
Senior Living Communities
Debt Instrument
Number of properties owned (property) | property		2											2
Unsecured Debt, Not Guaranteed
Debt Instrument
Principal amount of debt		$ 1,100,000,000											$ 1,100,000,000
Senior Unsecured Notes
Debt Instrument
Principal amount of debt		2,100,000,000											2,100,000,000	$ 2,350,000,000
Credit Facility | Unsecured debt
Debt Instrument
Unsecured revolving credit facility, maximum borrowing capacity		$ 450,000,000		$ 450,000,000	$ 586,373,000					$ 700,000,000			$ 450,000,000				$ 800,000,000
Credit facility, interest rate payable (as a percent)		8.40%											8.40%
Facility fee													$ 338,000
Weighted average interest rate on debt (as a percent)		7.90%											7.90%	4.50%	2.90%
Repayments of borrowings on revolving credit facility	$ 450,000,000	$ 450,000,000		136,373,000	$ 113,627,000					$ 100,000,000
Loss on modification or early extinguishment of debt		314,000		$ 1,075,000									$ (1,389,000)
Senior Secured Notes Due January 2026 | Secured Debt
Debt Instrument
Principal amount of debt	940,534,000	$ 940,534,000											$ 940,534,000
Interest rate (as a percent)		0.00%											0.00%
Proceeds from debt	730,359,000
Equity interest in each collateral guarantee													100.00%
Accreted value increase rate		11.25%											11.25%
Senior unsecured notes due 2025 | Senior Notes
Debt Instrument
Principal amount of debt		$ 500,000,000											$ 500,000,000
Interest rate (as a percent)		9.75%											9.75%
Senior unsecured notes due 2025 | Senior Unsecured Notes
Debt Instrument
Principal amount of debt		$ 500,000,000											$ 500,000,000	$ 500,000,000
Interest rate (as a percent)		9.75%											9.75%
Senior unsecured notes due 2031 | Senior Notes
Debt Instrument
Principal amount of debt		$ 500,000,000											$ 500,000,000
Interest rate (as a percent)		4.375%											4.375%
Senior unsecured notes due 2031 | Senior Unsecured Notes
Debt Instrument
Principal amount of debt		$ 500,000,000											$ 500,000,000	500,000,000
Interest rate (as a percent)		4.375%											4.375%
Senior Note 4.375 Due 2031 | Senior Unsecured Notes
Debt Instrument
Principal amount of debt											$ 500,000,000
Interest rate (as a percent)											4.375%
Proceeds from debt											$ 491,357,000
Term loan due 2022 | Senior Unsecured Notes
Debt Instrument
Principal amount of debt											$ 200,000,000
Loss on modification or early extinguishment of debt															$ 1,477,000
Debt instrument, interest rate during period												2.90%
Senior Unsecured Notes Due June 2021 | Senior Unsecured Notes
Debt Instrument
Principal amount of debt																		$ 300,000,000
Interest rate (as a percent)																		6.75%
Loss on modification or early extinguishment of debt															$ 370,000
Accrued interest																		$ 10,125,000
Mortgage notes 6.28% maturing July 2022 | Medical Office
Debt Instrument
Interest rate (as a percent)									6.28%
Number of properties owned (property) | property									1
Repayments of debt									$ 10,934,000
Mortgage notes 6.28% maturing July 2022 | Senior Living Communities
Debt Instrument
Interest rate (as a percent)							5.75%
Number of properties owned (property) | property							2
Repayments of debt							$ 15,273,000
Senior Unsecured Note Due 2025
Debt Instrument
Interest rate (as a percent)																9.75%
Loss on modification or early extinguishment of debt														29,576,000
Accrued interest																$ 1,083,000
Debt instrument, amount redeemed																$ 500,000,000
Redemption price (as a percent)								104.875%
Mortgages 4.85 Percent Matured In October 2022 | Life Science
Debt Instrument
Interest rate (as a percent)						4.85%
Number of properties owned (property) | property						1
Repayments of debt						$ 10,287,000
Mortgages
Debt Instrument
Interest rate (as a percent)			6.64%
Number of properties owned (property) | property			1
Repayments of debt			$ 14,565,000
Senior unsecured notes, 4.750% coupon rate, due 2024 | Senior Unsecured Notes
Debt Instrument
Principal amount of debt		$ 0											$ 0	$ 250,000,000
Interest rate (as a percent)		4.75%											4.75%
Loss on modification or early extinguishment of debt		$ 1,079,000
Redemption of senior unsecured notes	$ 250,000,000	$ 250,000,000